There is available a batch-type substrate processing apparatus configured such that, in a state in which a substrate holder for holding substrates at multiple stages is loaded into a reaction furnace, the substrates held by the substrate holder are processed by supplying a process gas into the reaction furnace. For example, Patent Document 1 recites that a maintenance information image is displayed on an operation screen. Thus, the maintenance time of components constituting a substrate processing apparatus can be determined based on the use frequency of the respective components or the processing time.
Conventionally, in a substrate processing apparatus, each component that has reached a maintenance time is replaced by a new component. Therefore, the substrate processing apparatus is stopped. However, in recent years, from the viewpoint of improving an apparatus operation rate and automating an interior of a factory, it has been required to operate an apparatus in such a way as not to stop the apparatus as far as possible. Even in a vertical batch-type substrate processing apparatus, by executing a maintenance-purpose recipe from this viewpoint, a predetermined cleaning gas is supplied to remove byproducts adhering to members (a reaction tube, a substrate holder, etc.) that constitute an interior of a reaction furnace. For example, Patent Document 2 discloses that a deposit adhering to an inner wall of a reaction tube and so forth is removed by supplying a cleaning gas into the reaction tube. Furthermore, according to Patent Document 3, in a single-substrate-type substrate processing apparatus, if a deposited film deposited within a process chamber reaches a threshold value, a maintenance-purpose recipe is executed to remove an accumulated deposited film.
Incidentally, a step time for supplying a cleaning gas is calculated by calculating a cleaning completion time in advance and is set at the time thus calculated. Thus, it is not possible to determine whether the cleaning has been completed. In the meantime, if a film forming process is repeatedly performed, byproducts are generated. If the byproducts are left alone, they remain adhering to individual components which constitute an apparatus, thereby adversely affecting film formation. Thus, gas cleaning is performed at a predetermined period.
Conventionally, determination of completion of cleaning is made using a phenomenon that a temperature rise is generated by reaction heat at a cleaning time. That is to say, there has been used a method in which completion of cleaning is determined by setting a predetermined pre-cleaning temperature as a threshold value, comparing the threshold value with a predetermined measured value (temperature), and determining whether a pre-cleaning state comes back. However, in this method, an error is large and determination of completion of cleaning cannot be properly made.